During blast hole drilling for obtaining ore from ore bodies, that are disposed in thin strata (order of magnitude below one meter thick) a technology is used, wherein the aim is to avoid extracting more than necessary of the surrounding, non ore bearing rock. For that reason the drifts are made with as small dimensions as possible, and in particular as low as possible. Further, drill rigs are used which are operative in the ore body between the drifts, said drill rigs allowing extraction of ore and rock with a height just over about one meter in height.
It can be mentioned that as alternatives to such minimalized drill rigs, it is possible to further reduce the extraction of rock by means of handheld equipment. This at the price of inferior working environment for the workers.
A previously known drill rig of the above kind has been put on the market under the name “Stomec”. The basic idea with this previously known drill rig was to separate the power unit, including motor-hydraulic pump, from the rig itself, which is provided with propulsion means in the form of crawlers, and a rig body, whereupon a boom with two feed beams is attached.
A tube arrangement supplies the rig unit with hydraulic oil, water and pressure air from the power unit.
Another example of the background art is a drill rig, having a conventional feeder, being supported by a short beam on each one of the front and rear sides of the rig. In this rig the motor and pump unit are disposed in the rig body and propulsion of the rig as well as operation of the drilling machines on the feeders is controlled over a radio link. This latter drill rig has i.a. the drawback that several functions are doubled, for example through the present of double beams, which results in increased costs. The rig further allows only drilling in one single direction which is a disadvantage in many narrow drift areas.